![]() |
Intuitionistic Logic Explorer |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > ILE Home > Th. List > nn0ehalf | GIF version |
Description: The half of an even nonnegative integer is a nonnegative integer. (Contributed by AV, 22-Jun-2020.) (Revised by AV, 28-Jun-2021.) |
Ref | Expression |
---|---|
nn0ehalf | ⊢ ((𝑁 ∈ ℕ0 ∧ 2 ∥ 𝑁) → (𝑁 / 2) ∈ ℕ0) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nn0z 9271 | . . . 4 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℤ) | |
2 | evend2 11888 | . . . 4 ⊢ (𝑁 ∈ ℤ → (2 ∥ 𝑁 ↔ (𝑁 / 2) ∈ ℤ)) | |
3 | 1, 2 | syl 14 | . . 3 ⊢ (𝑁 ∈ ℕ0 → (2 ∥ 𝑁 ↔ (𝑁 / 2) ∈ ℤ)) |
4 | nn0ge0 9199 | . . . . . . . 8 ⊢ (𝑁 ∈ ℕ0 → 0 ≤ 𝑁) | |
5 | nn0re 9183 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℝ) | |
6 | 2re 8987 | . . . . . . . . . 10 ⊢ 2 ∈ ℝ | |
7 | 6 | a1i 9 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 2 ∈ ℝ) |
8 | 2pos 9008 | . . . . . . . . . 10 ⊢ 0 < 2 | |
9 | 8 | a1i 9 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 0 < 2) |
10 | ge0div 8826 | . . . . . . . . 9 ⊢ ((𝑁 ∈ ℝ ∧ 2 ∈ ℝ ∧ 0 < 2) → (0 ≤ 𝑁 ↔ 0 ≤ (𝑁 / 2))) | |
11 | 5, 7, 9, 10 | syl3anc 1238 | . . . . . . . 8 ⊢ (𝑁 ∈ ℕ0 → (0 ≤ 𝑁 ↔ 0 ≤ (𝑁 / 2))) |
12 | 4, 11 | mpbid 147 | . . . . . . 7 ⊢ (𝑁 ∈ ℕ0 → 0 ≤ (𝑁 / 2)) |
13 | 12 | anim1i 340 | . . . . . 6 ⊢ ((𝑁 ∈ ℕ0 ∧ (𝑁 / 2) ∈ ℤ) → (0 ≤ (𝑁 / 2) ∧ (𝑁 / 2) ∈ ℤ)) |
14 | 13 | ancomd 267 | . . . . 5 ⊢ ((𝑁 ∈ ℕ0 ∧ (𝑁 / 2) ∈ ℤ) → ((𝑁 / 2) ∈ ℤ ∧ 0 ≤ (𝑁 / 2))) |
15 | elnn0z 9264 | . . . . 5 ⊢ ((𝑁 / 2) ∈ ℕ0 ↔ ((𝑁 / 2) ∈ ℤ ∧ 0 ≤ (𝑁 / 2))) | |
16 | 14, 15 | sylibr 134 | . . . 4 ⊢ ((𝑁 ∈ ℕ0 ∧ (𝑁 / 2) ∈ ℤ) → (𝑁 / 2) ∈ ℕ0) |
17 | 16 | ex 115 | . . 3 ⊢ (𝑁 ∈ ℕ0 → ((𝑁 / 2) ∈ ℤ → (𝑁 / 2) ∈ ℕ0)) |
18 | 3, 17 | sylbid 150 | . 2 ⊢ (𝑁 ∈ ℕ0 → (2 ∥ 𝑁 → (𝑁 / 2) ∈ ℕ0)) |
19 | 18 | imp 124 | 1 ⊢ ((𝑁 ∈ ℕ0 ∧ 2 ∥ 𝑁) → (𝑁 / 2) ∈ ℕ0) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ↔ wb 105 ∈ wcel 2148 class class class wbr 4003 (class class class)co 5874 ℝcr 7809 0cc0 7810 < clt 7990 ≤ cle 7991 / cdiv 8627 2c2 8968 ℕ0cn0 9174 ℤcz 9251 ∥ cdvds 11789 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 ax-io 709 ax-5 1447 ax-7 1448 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-8 1504 ax-10 1505 ax-11 1506 ax-i12 1507 ax-bndl 1509 ax-4 1510 ax-17 1526 ax-i9 1530 ax-ial 1534 ax-i5r 1535 ax-13 2150 ax-14 2151 ax-ext 2159 ax-sep 4121 ax-pow 4174 ax-pr 4209 ax-un 4433 ax-setind 4536 ax-cnex 7901 ax-resscn 7902 ax-1cn 7903 ax-1re 7904 ax-icn 7905 ax-addcl 7906 ax-addrcl 7907 ax-mulcl 7908 ax-mulrcl 7909 ax-addcom 7910 ax-mulcom 7911 ax-addass 7912 ax-mulass 7913 ax-distr 7914 ax-i2m1 7915 ax-0lt1 7916 ax-1rid 7917 ax-0id 7918 ax-rnegex 7919 ax-precex 7920 ax-cnre 7921 ax-pre-ltirr 7922 ax-pre-ltwlin 7923 ax-pre-lttrn 7924 ax-pre-apti 7925 ax-pre-ltadd 7926 ax-pre-mulgt0 7927 ax-pre-mulext 7928 |
This theorem depends on definitions: df-bi 117 df-3or 979 df-3an 980 df-tru 1356 df-fal 1359 df-nf 1461 df-sb 1763 df-eu 2029 df-mo 2030 df-clab 2164 df-cleq 2170 df-clel 2173 df-nfc 2308 df-ne 2348 df-nel 2443 df-ral 2460 df-rex 2461 df-reu 2462 df-rmo 2463 df-rab 2464 df-v 2739 df-sbc 2963 df-dif 3131 df-un 3133 df-in 3135 df-ss 3142 df-pw 3577 df-sn 3598 df-pr 3599 df-op 3601 df-uni 3810 df-int 3845 df-br 4004 df-opab 4065 df-id 4293 df-po 4296 df-iso 4297 df-xp 4632 df-rel 4633 df-cnv 4634 df-co 4635 df-dm 4636 df-iota 5178 df-fun 5218 df-fv 5224 df-riota 5830 df-ov 5877 df-oprab 5878 df-mpo 5879 df-pnf 7992 df-mnf 7993 df-xr 7994 df-ltxr 7995 df-le 7996 df-sub 8128 df-neg 8129 df-reap 8530 df-ap 8537 df-div 8628 df-inn 8918 df-2 8976 df-n0 9175 df-z 9252 df-dvds 11790 |
This theorem is referenced by: nnehalf 11903 |
Copyright terms: Public domain | W3C validator |